Radiomic analysis of patient and inter-organ heterogeneity in response to immunotherapies and BRAF targeted therapy in metastatic melanoma

Background

Variability in treatment response may be attributable to organ-level heterogeneity in tumor lesions. Radiomic analysis of medical images can elucidate non-invasive biomarkers of clinical outcome. Organ-specific radiomic comparison across immunotherapies and targeted therapies has not been previously reported.

Methods

We queried UPMC Hillman Cancer Center registry for patients with metastatic melanoma (MEL) treated with immune checkpoint inhibitors (ICI) (anti-PD1/CTLA4 [ipilimumab+nivolumab; I+N] or anti-PD1 monotherapy) or BRAF targeted therapy. Best overall response was measured using RECIST v1.1. Lesions were segmented into discrete volume-of-interest with 400 radiomics features extracted. Overall and organ-specific machine-learning models were constructed to predict disease control (DC) versus progressive disease (PD) using XGBoost.

Results

291 MEL patients were identified, including 242 ICI (91 I+N, 151 PD1) and 49 BRAF. 667 metastases were analyzed, including 541 ICI (236 I+N, 305 PD1) and 126 BRAF. Across cohorts, baseline demographics included 39-47% female, 24-29% M1C, 24-46% M1D, and 61-80% with elevated LDH. Among patients experiencing DC, the organs with the greatest reduction were liver (-88%±12%, I+N; mean±S.E.M.) and lung (-72%±8%, I+N). For patients with multiple same-organ target lesions, the highest inter-lesion heterogeneity was observed in brain among patients who received ICI while no intra-organ heterogeneity was observed in BRAF. 267 patients were kept for radiomic modeling, including 221 ICI (86 I+N, 135 PD1) and 46 BRAF. Models consisting of optimized radiomic signatures classified DC/PD across I+N (AUC=0.85) and PD1 (0.71) and within individual organ sites (AUC=0.72∼0.94). Integration of clinical variables improved the models' performance. Comparison of models between treatments and across organ sites suggested mostly non-overlapping DC or PD features. Skewness, kurtosis, and informational measure of correlation (IMC) were among the radiomic features shared between overall response models. Kurtosis and IMC were also utilized by multiple organ-site models.

Conclusions

Differential organ-specific response was observed across BRAF and ICI with within organ heterogeneity observed for ICI but not for BRAF. Radiomic features of organ-specific response demonstrated little overlap. Integrating clinical factors with radiomics improves the prediction of disease course outcome and prediction of tumor heterogeneity.

TONI - One for all? Participatory development of a transtheoretic and transdiagnostic online intervention for blended care

Background

Internet-based interventions offer a way to meet the high demand for psychological support. However, this setting also has disadvantages, such as the lack of personal contact and the limited ability to respond to crises. Blended care combines Internet-based interventions with face-to-face psychotherapy and merges the benefits of both settings. To ensure the uptake of blended care in routine care, Internet-based interventions need to be suitable for different therapeutic approaches and mental disorders.

Objective

This paper describes the participatory development process of the Internet-based intervention "TONI" using a common therapeutic language and content on various transdiagnostic topics to be integrated into routine outpatient psychotherapy.

Methods

To develop this intervention in a participatory manner, we followed the Integrate, Design, Assess, and Share (IDEAS) framework. In a multilevel development process, we used a combination of interviews, focus groups, and proofreading to optimally tailor online modules to routine outpatient psychotherapy. Building on well-established cognitive-behavioral online content, we included expert interviews with psychodynamic (n = 20) and systemic psychotherapists (n = 9) as well as focus groups with psychotherapists of different approaches (n = 10) and persons with lived experience of mental illness (PWLE; n = 10).

Results

We describe the development process of TONI step-by-step, outlining the specific requirements that therapists from different therapeutic approaches as well as PWLE have and how we implemented them in our intervention. This includes the content and specific exercises in the online modules, aspects of data protection, language, design, and usability.

Conclusion

Internet-based interventions that use a common therapeutic language and address therapeutic principles across different approaches have the potential to advance digitalization in psychotherapy. Involving psychotherapists and PWLE in intervention development may positively impact acceptance and usage in practice. This study shows how participatory intervention development involving both psychotherapists and PWLE can be carried out.

Tumor cell p38 inhibition to overcome immunotherapy resistance

Patients with tumors that do not respond to immune-checkpoint inhibition often harbor a non-T cell-inflamed tumor microenvironment, characterized by the absence of IFN-γ-associated CD8+ T cell and dendritic cell activation. Understanding the molecular mechanisms underlying immune exclusion in non-responding patients may enable the development of novel combination therapies. p38 MAPK is a known regulator of dendritic and myeloid cells however a tumor-intrinsic immunomodulatory role has not been previously described. Here we identify tumor cell p38 signaling as a therapeutic target to potentiate anti-tumor immunity and overcome resistance to immune-checkpoint inhibitors (ICI). Molecular analysis of tumor tissues from patients with human papillomavirus-negative head and neck squamous carcinoma reveals a p38-centered network enriched in non-T cell-inflamed tumors. Pan-cancer single-cell RNA analysis suggests that p38 activation may be an immune-exclusion mechanism across multiple tumor types. P38 knockdown in cancer cell lines increases T cell migration, and p38 inhibition plus ICI in preclinical models shows greater efficacy compared to monotherapies. In a clinical trial of patients refractory to PD1/L1 therapy, pexmetinib, a p38 inhibitor, plus nivolumab demonstrated deep and durable clinical responses. Targeting of p38 with anti-PD1 has the potential to induce the T cell-inflamed phenotype and overcome immunotherapy resistance.

Abstract 2800: Pharmacokinetics, bioavailability, and pharmacodynamics of oral triapine

Background: Locally advanced cervical cancer accounts for most deaths from disease. Standard of care includes treatment with cisplatin-based chemoradiation with a 70% response rate. The addition of intravenous (IV) triapine to chemoradiation has shown promising clinical activity in phase 1 and 2 studies but comes with a more intensive treatment regimen. An ongoing phase 1 trial has finished the escalation phase, and we report the pharmacokinetics (PK) and pharmacodynamics (PD) of oral (PO) triapine.

Methods: This phase 1 study followed a 3+3 design for dose escalation of oral triapine, starting with initial dose of 100 mg five days a week for five weeks combined with external beam pelvic radiation and weekly IV cisplatin. PK was determined by LC-MS/MS, and PD included methemoglobin levels at 4 h post dose. Within patient PK variability after IV and PO dosing and PO bioavailability were calculated.

Results: PK data were available for 10 patients at 100 (the MTD) and 150 mg. PO parameter values were Tmax 1.3 h, t1/2 1.4 h, CL/F 104 L/h, and Vz/F 214 L. There was no discernable difference between triapine exposure at 100 vs. 150 mg PO (Cmax 520 (2.5) vs. 344 (1.9) µg/L; AUC 1209 (2.53) vs. 1034 (1.41) µg/L•h), and between patient variability at each dose level was substantial. The correlation of PO Vz/F vs Cl/F was high at R2=0.86, suggesting that the apparent clearance and volume variability is primarily due to variability in the oral bioavailability F. PO within patient variability of Cmax and AUC was also large at 43% and 55%. IV PK was less variable with lower geometric standard deviations across all parameters, including within patients where variability of Cmax and AUC was modest at 10 and 12% coefficient of variation, respectively. Oral bioavailability was estimated at 66%. We found a non-significant trend of smoking almost doubling triapine oral clearance from 68 to 156 L/h (p=0.056). There was no apparent relationship between occurrence of DLT and either IV or PO triapine AUC. Methemoglobin levels directly correlated with triapine exposure expressed as AUC or Cmax.

Conclusions: Triapine PK parameter values for PO and IV administration and PO bioavailability values observed in this trial were comparable to previous reports. Correlation of methemoglobin with exposure highlights the importance of optimizing triapine exposure. Additional data may support the exploration of a dose specific to current smokers.

Citation Format: Jan H. Beumer, Sarah Behr, Holly Gallion, John Vargo, Frederick Ueland, Haider Mahdi, Brian Orr, Eugenia Girda, Susan Christner, Edward Chu, Charles Kunos, Percy S. Ivy, Sarah Taylor. Pharmacokinetics, bioavailability, and pharmacodynamics of oral triapine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2800.

Surgical techniques used in the management of intra-arachnoid diverticula in dogs across four referral centres and their immediate outcome

OBJECTIVES

To report the surgical techniques being used to treat single focal spinal intra-arachnoid diverticula in dogs, their complications and immediate postoperative outcomes.

MATERIALS AND METHODS

Retrospective multi-centre case series across four referral centres.

RESULTS

Fifty-seven dogs were included in the study. The most common type of surgery was durectomy (28 dogs) followed by marsupialisation (11 dogs), durotomy alone (seven dogs), shunt placement (six dogs) and stabilisation (five dogs). A higher proportion of intra-arachnoid shunt dogs became unable to walk in the immediate postoperative period (24 hours postsurgery) (4/6, 66%) compared to all dogs five of 57, 9% (2/7 durotomy alone, 3/28 durectomy alone). Of the nine dogs with immediate postoperative deterioration, seven had improved, walking without assistance, by 3 to 5 weeks postoperatively.

CLINICAL SIGNIFICANCE

This study does not identify an influence of surgical technique on short-term outcome. Dogs with a thoracolumbar intra-arachnoid diverticulum that undergo a shunt placement are likely to deteriorate neurologically in the immediate 24-hour postoperative period but appear to improve by 3 to 5 weeks after surgery. Further work is required to evaluate whether one surgical technique is superior for preventing or reducing long-term relapse.

Astrocytes and Microglia Are Resistant to NAD+-Mediated Cell Death Along the ARTC2/P2X7 Axis

ADP-ribosylation of the P2X7k splice variant on mouse T cells by Ecto-ADP-ribosyltransferase ARTC2.2 in response to its substrate extracellular nicotinamide adenine dinucleotide (NAD⁺) triggers cell death. Since NAD⁺ is released as a danger signal during tissue damage, this NAD⁺-induced cell death (NICD) may impact the survival of other cell populations co-expressing P2X7 and of one of the ARTC2 isoforms (ARTC2.1, ARTC2.2). NICD of brain-resident, non-T cell populations has only been rudimentarily investigated. In this study, we evaluated the susceptibility of two glia cell populations, astrocytes and microglia, towards NICD. We found that astrocytes and microglia strongly upregulate cell surface levels of ARTC2.1 and ADP-ribosylation of cell surface proteins in response to treatment with lipopolysaccharide (LPS) and the mitogen-activated protein kinase kinase (MEK) 1 and 2 inhibitor U0126, but do not respond to extracellular NAD⁺ with P2X7 activation and induction of cell death. Furthermore, we found that astrocytes and microglia preferentially express the ADP-ribosylation-insensitive P2X7a splice variant, likely accounting for the resistance of these cells to NICD.

Ecto-ADP-ribosyltransferase ARTC2.1 functionally modulates FcγR1 and FcγR2B on murine microglia

Mammalian ecto-ADP-ribosyltransferases (ecto-ARTs or also ARTCs) catalyze the ADP-ribosylation of cell surface proteins using extracellular nicotinamide adenine dinucleotide (NAD⁺) as substrate. By this post-translational protein modification, ecto-ARTs modulate the function of various target proteins. A functional role of ARTC2 has been demonstrated for peripheral immune cells such as T cells and macrophages. Yet, little is known about the role of ecto-ARTs in the central nervous system and on microglia. Here, we identified ARTC2.1 as the major ecto-ART expressed on murine microglia. ARTC2.1 expression was strongly upregulated on microglia upon co-stimulation with LPS and an ERK1/2 inhibitor or upon IFNβ stimulation. We identified several target proteins modified by ARTC2.1 on microglia with a recently developed mass spectrometry approach, including two receptors for immunoglobulin G (IgG), FcγR1 and FcγR2B. Both proteins were verified as targets of ARTC2.1 in vitro using a radiolabeling assay with ³²P-NAD⁺ as substrate. Moreover, ADP-ribosylation of both targets strongly inhibited their capacity to bind IgG. In concordance, ARTC2.1 induction in WT microglia and subsequent cell surface ADP-ribosylation significantly reduced the phagocytosis of IgG-coated latex beads, which was unimpaired in NAD⁺/DTT treated microglia from ARTC2.1^-/- mice. Hence, induction of ARTC2.1 expression under inflammatory conditions, and subsequent ADP-ribosylation of cell surface target proteins could represent a hitherto unnoticed mechanism to regulate the immune response of murine microglia.

Comparison of basal insulin therapies with regard to the risk of acute myocardial infarction in patients with type 2 diabetes: an observational cohort study

AIMS

To assess the risk of acute myocardial infarction (AMI) in patients with type 2 diabetes mellitus treated with long-acting insulin analogues in comparison with other basal insulin therapy.

METHODS

We used German insurance claims data from the years 2004-2009 to conduct a study in a retrospective cohort of patients with type 2 diabetes. Naïve insulin users were defined as patients who had an insulin-free history before the first prescription of long-acting analogue insulin, human NPH insulin or premixed insulin and who were pretreated with oral antidiabetic drugs. Adjusted hazard ratios (HRs) of AMI and corresponding 95% confidence intervals (CIs) were calculated using sex-stratified Cox models. Propensity-score-matched analyses were conducted as sensitivity analyses.

RESULTS

We identified 21,501 new insulin users. Patients treated with premixed insulin were older than patients treated with analogue or NPH insulin (mean age 70.7 vs. 64.1 and 61.6 years, respectively) and had more comorbidities. Regarding the risk of AMI, adjusted HRs showed no statistically significant difference between NPH and analogue insulin (HR 0.94, 95% CI 0.74-1.19), but a higher risk for premixed than for analogue insulin (HR 1.27, 95% CI 1.02-1.58). Contrary to the primary analysis, the propensity-score-matched analysis did not show an increased risk for premixed insulin.

CONCLUSIONS

In contrast to a former database study, no difference was observed for the risk of AMI between long-acting analogue and NPH insulin in this study. Neither long-acting analogue insulin nor premixed insulin appears to be associated with AMI in patients with type 2 diabetes.

The combination of axitinib followed by paclitaxel/carboplatin yields extended survival in advanced BRAF wild-type melanoma: results of a clinical/correlative prospective phase II clinical trial

BACKGROUND

Simultaneous chemotherapy with vascular endothelial growth factor (VEGF) inhibition has not shown additional benefit over chemotherapy alone in advanced melanoma. We tested administration of the potent VEGF inhibitor axitinib followed by paclitaxel/carboplatin to determine whether enhanced tumour proliferation during axitinib withdrawal leads to sustained chemosensitivity.

METHODS

We conducted a prospective phase II trial in metastatic melanoma patients with ECOG performance status 0-1 and normal organ function. Axitinib 5 mg PO b.i.d. was taken on days 1-14 of each 21-day treatment cycle, and carboplatin (AUC=5) with paclitaxel (175 mg m(-2)) was administered on day 1 starting with cycle 2. 3'-Deoxy-3'-(18)F-fluorothymidine ((18)F-FLT)-PET scans were performed in five patients to assess tumour proliferation on days 1, 14, 17, and 20 of cycle 1. Molecular profiling for BRAF was performed for all patients with cutaneous, acral, or mucosal melanoma.

RESULTS

The treatment was well tolerated. The most common grade 3 AEs were hypertension, neutropenia, and anaemia. Grade 4 non-haematologic AEs were not observed. Four of five patients completing (18)F-FLT-PET scans showed increases (23-92%) in SUV values during the axitinib holiday. Of 36 evaluable patients, there were 8 confirmed PRs by Response Evaluation Criteria in Solid Tumors. Overall, 20 patients had SD and 8 had PD as the best response. The median PFS was 8.7 months and the median overall survival was 14.0 months. Five BRAF(V600E/K) patients had significantly worse PFS than patients without these mutations.

CONCLUSIONS

Axitinib followed by carboplatin and paclitaxel was well tolerated and effective in BRAF wild-type metastatic melanoma. 3'-Deoxy-3'-(18)F-fluorothymidine-PET scans showed increased proliferation during axitinib withdrawal.

Diagnosis of Cardiac Metastasis from Endometrial Cancer by F-18 FDG-PET/CT

We report a case of a 59-year-old woman with right ventricular metastasis of undifferentiated endometrial cancer. Cardiac metastasis from endometrial cancer is a very rare finding. The case demonstrates that undifferentiated endometrial cancer is capable of metastasizing, presumably through a hematogenous route, to unexpected distant organs. These unexpected sites should not be undermined in the restaging and surveillance of these patients.

Porencephaly and hydranencephaly in six dogs

A retrospective study was performed to identify dogs with cerebrospinal fluid-filled cavitatory lesions on MRI. Six dogs were included and the lesions were classified. In the three dogs in the present study with hydranencephaly, unilateral but complete loss of the temporal and parietal lobes was noted and had almost complete loss of the occipital and frontal lobes of a cerebral hemisphere. In the three dogs with porencephaly, there was unilateral incomplete loss of the parietal lobe and one dog had additional partial loss of the temporal and frontal lobes. Two of the dogs with porencephaly had seizures; the third showed no associated clinical signs. The dogs with hydranencephaly had mentation changes and circled compulsively. The two porencephalic dogs with seizures were treated with phenobarbitone. One of the dogs with hydranencephaly showed increased frequency and duration of circling; one dog's clinical signs did not progress and the third dog was euthanased due to increasing aggression. The dog with increased circling had ventriculoperitoneal shunt placement and the circling frequency reduced.

A novel movement disorder in related male Labrador Retrievers characterized by extreme generalized muscular stiffness

OBJECTIVES

To describe the clinical phenotype of a new motor disorder in Labrador Retrievers.

ANIMALS AND METHODS

Case series study. Seven young male Labrador Retrievers presented for evaluation of stiff gait.

RESULTS

All affected dogs had generalized muscular stiffness, persistent at rest and resulting in restricted joint movements. They showed a forward flexed posture, festinating gait, and bradykinesia. Signs developed between 2 and 16 months of age and tended to stabilize in adulthood. Needle electromyogram in the conscious state showed continuous motor unit activity in resting epaxial and proximal limb muscles. This activity was abolished by general anesthesia. Muscle and nerve histopathology was normal. In 2 dogs necropsied, astrocytosis was evident throughout the spinal cord gray matter, reticular formation and caudate nuclei. Decreased neuronal counts were selectively found in the spinal cord Rexed's lamina VII, but not in VIII and IX. Pedigree analysis showed that the affected dogs were from 5 related litters.

CONCLUSIONS AND CLINICAL IMPORTANCE

This new hypertonicity syndrome in Labrador Retrievers is unique because of the selective distribution of the histological lesions, the lack of progression in adulthood, and its exclusive occurrence in male dogs. Pedigree analysis suggests an X-linked hereditary disease, although other modes of inheritance cannot be ruled out with certainty. We hypothesize that altered output from basal nuclei and reticular formation together with motor neuron disinhibition caused by a decreased number of spinal cord interneurons leads to the muscular stiffness.

Assessment of a pyrogallol red technique for total protein measurement in the cerebrospinal fluid of dogs

The measurement of protein concentration in the cerebrospinal fluid is a basic analytical method in neurology. In this study, a pyrogallol red technique using a human albumin calibrator previously validated in human medicine was tested for canine samples, and the results were compared with those obtained using urine test strips. Pyrogallol red significantly (P<0.05) but moderately underestimated purified dog albumin and globulins. The imprecision of the technique was low: intra- and between-series coefficients of variation were 1.6 and 4.3 per cent at protein concentrations of about 0.3 g/litre. Over 49 samples, there was good agreement between the pyrogallol red and test strip results (r=0.63), especially for low and high protein concentrations, but misclassifications were observed with '+' test strip readings.

Low levels of viscous hydrocolloids lower plasma cholesterol in rats primarily by impairing cholesterol absorption

Hydrocolloids have been proposed as cholesterol-lowering agents, but their viscosity limits their use in human nutrition. A low level (1 %) of hydrocolloids (guar gum, (GG); xanthan gum, (XG); and konjac mannan) was investigated in rats fed 0.2 g/100 g cholesterol diets. Food intake and body weight gain were not altered by the diets. Bile flow and cholesterol bile flux were not modified by diet, whereas the bile acid flux was greater in rats fed hydrocolloid diets. The cecal pool of bile acids was greater than control rats only in rats fed the XG diet (+71%, P<0.001). The fecal excretion of neutral sterols was stimulated in rats fed the hydrocolloid diets; cholesterol apparent digestibility (60% in controls) was reduced to 30-36% in rats fed hydrocolloids. Bile acid fecal excretion was not altered by diet treatment. As a result, apparent steroid balance was about +40 micromol/d in controls and only +10 to +20 micromol/d in rats fed hydrocolloids. Both plasma cholesterol and triglycerides were significantly lower than controls in rats fed XG, but only cholesterol was lower in rats fed the GG diet. These effects were essentially found in the d <1.040 kg/L fraction. Liver cholesterol content was significantly lower than in controls in rats fed the GG or XG diets. Liver HMG CoA reductase was not affected by the hydrocolloid diets. In conclusion, a low percentage of viscous hydrocolloids lowers plasma cholesterol in cholesterol-fed rats. Inhibition of intestinal cholesterol absorption may be the primary mechanism.

A fully automated multicapillary electrophoresis device for DNA analysis

We describe the construction and performance of a fully automated multicapillary electrophoresis system for the analysis of fluorescently labeled biomolecules. A special detection system allows the simultaneous spectral analysis of all 96 capillaries. The main features are true parallel detection without any moving parts, high robustness, and full compatibility to existing protocols. The device can process up to 40 microtiter plates (96 and 384 well) without human interference, which means up to 15,000 samples before it has to be reloaded.

Fermentable carbohydrate exerts a urea-lowering effect in normal and nephrectomized rats

The influence of nondigestible carbohydrate on intestinal fermentations and on the route of nitrogen excretion has been investigated in normal rats and in unilaterally nephrectomized rats. Rats were adapted to 10% casein diets, either fiber free or containing different levels of two fermentable carbohydrates, inulin or crude potato starch. Ingestion of fermentable carbohydrate led to a considerable enlargement of the cecum because of hypertrophy of the cecal wall and an increase in cecal contents. Cecal digesta contained elevated concentrations of short-chain fatty acids, resulting in acidic pH. Diets containing fermentable carbohydrate enhanced fecal nitrogen excretion, which was more than doubled at the highest level of inulin or potato starch. In parallel, urinary nitrogen excretion was significantly decreased by fermentable carbohydrate. Although these changes were similar in all animals, there were quantitative differences in the response of nephrectomized animals to fermentable carbohydrate. In nephrectomized rats, plasma urea concentrations were more than 2.5 times higher than in normal rats (5.8 mM compared with 2.2 mM). Plasma urea concentrations were reduced by approximately 50% when normal rats were fed diets containing 7.5-15% inulin or 10-20% resistant starch. In nephrectomized animals fed the highest level of fermentable carbohydrate, plasma urea concentrations were also significantly decreased, but only by 30%. In nephrectomized rats, the concentration of nitrogen cycling in the cecum was greater (urea nitrogen transfer into the cecum was 50-60% greater and ammonia flux from the cecal lumen to the blood was two times higher than in normal rats), but fecal nitrogen excretion was equivalent in normal and nephrectomized animals. When expressed as a percentage of total nitrogen excretion, fecal nitrogen excretion was <20% in animals fed fiber-free diets, compared with 45-50% in normal animals and 40% in nephrectomized animals fed fermentable carbohydrate.

Engaging CD19 or target of an antiproliferative antibody 1 on human B lymphocytes induces binding of B cells to the interfollicular stroma of human tonsils via integrin alpha 4/beta 1 and fibronectin

Adhesion of B lymphocytes within the different compartments of secondary lymphoid organs is essential for the function of the humoral immune response. It is not currently known how the temporary immobilization of B cells in distinct areas of this complex microenvironment is regulated. The present study aimed at defining B cell antigens that initiate binding of B cells to human tonsil sections in situ. Engaging the B cell antigens CD19 and target of an antiproliferative antibody 1 (TAPA-1) with monoclonal antibodies induced adhesion of these B cells to the interfollicular stroma. This binding occurred through the integrin alpha 4 beta 1 on the B cell surface and via the extracellular matrix protein fibronectin expressed in the interfollicular compartment of the tonsil. Signaling through either antigen, CD19 or TAPA-1, depended on tyrosine kinases. Binding induced by engaging CD19 required an intact cytoskeleton, whereas TAPA-1-transmitted adhesion did not. We suggest that CD19 and TAPA-1 have a novel and unique function by regulating an alpha 4 beta 1/fibronectin-mediated binding of B cells to the interfollicular stroma of lymphoid tissues.

Fermentable fibers or oligosaccharides reduce urinary nitrogen excretion by increasing urea disposal in the rat cecum

The availability of fermentable carbohydrates could influence the digestive degradation and disposal of blood urea. The effects of a poorly fermented cellulosic oat fiber, a soluble fermentable fiber (gum arabic) or one of two oligosaccharides (fructooligosaccharide or xylooligosaccharide) on nitrogen excretion were compared with a wheat starch-based control diet in male Wistar rats. The fibers and oligosaccharides were added to the semipurified diets at 7.5 g/100 g in place of wheat starch. The diets contained 13 g casein/100 g. Oat fiber did not cause an enlargement of the cecum. In contrast, gum arabic and the oligosaccharides elicited a 35-60% enlargement of the cecal wall and a 2 to 2.6-fold mean increase in the cecal pool of short chain fatty acids. Compared with rats fed the oat fiber-based diet, urea flux from blood to cecum was nearly 50% greater and more than 120% greater in those fed the gum arabic and oligosaccharide diets, respectively. In those groups, net nitrogen retention in the cecum more than doubled (nitrogen retention was calculated as the difference between net urea nitrogen flux into the cecum and ammonia nitrogen reabsorption). As a percentage of total excreted nitrogen, fecal nitrogen was 20% in the oat fiber group and 27-29% in the gum arabic and oligosaccharide groups, compared with only 10% in fiber-free controls. Results indicate that under these dietary conditions, the addition of oligosaccharides to the diet induced a 20 to 30% decrease in blood urea and renal and renal nitrogen excretion relative to the control, indicating a potential for oligosaccharide diet therapy in chronic renal disease.

The effect of esmolol given during cardiopulmonary bypass

beta-Adrenergic antagonism decreases the size of myocardial infarction and provides myocardial protection during hypothermic arrest for cardiac surgery. However, concern regarding the negative inotropic and chronotropic effects of beta-adrenergic antagonism persisting after cardiopulmonary bypass (CPB) has impeded the use of esmolol for this purpose during cardiac surgery. This is a randomized, double-blind prospective study of the effects of esmolol infused during CPB and the effects of hypothermic CPB on esmolol. Patients scheduled for CPB were randomized to receive intravenous esmolol (300.micrograms.kg-1.min-1 during CPB after a bolus of 2 mg/kg prior to CPB) or placebo. Infusion was stopped at 10 min after release of aortic cross-clamp. Hemodynamics were measured, as well as serum esmolol, catecholamines, lactate, and potassium. Postoperative variables measured included electrocardiographic changes, creatine kinase (CK)-MB fractions, post-CPB dysrhythmias and drugs, hospitalization time and cost, and mortality. Esmolol was administered to 16 patients and placebo to 14. Esmolol levels reached a high of 10.5 +/- 0.9 micrograms/mL during CPB, but decreased to 0.1 +/- 0.02 microgram/mL within 30 min after stopping infusion. Cardiac indices (cardiac index, stroke volume index, left cardiac work index, left ventricular stroke work index, right cardiac work index, and right ventricular stroke work index) were higher in the esmolol group for the first hour post-CPB (P < 0.05). Systemic arterial lactate and coronary sinus lactate were lower in the esmolol group after CPB (P < 0.05), but myocardial lactate extraction was not significantly different between groups. After CPB, hemoglobin was lower in the esmolol group (P < 0.05) due to longer CPB and aortic cross-clamp time (P < 0.05), but oxygen consumption was less than in the control group (P < 0.05). Post-CPB serum potassium was higher in the esmolol group (P < 0.05). Results are confounded by more chronically beta-adrenergically blocked patients randomized to the esmolol group (P < 0.05). Esmolol infused during CPB in this series of patients was associated with high concentrations during CPB but did not result in any adverse clinical effects after CPB.

Symptomatic mumps virus reinfections

Although natural mumps virus infection is believed to induce lifelong immunity, our laboratory was confronted with 82 patients who developed mumps-evoking lesions but exhibited serological evidence of a booster immune response, namely a rise or a high titer of virus-specific IgG, without IgM. In order to provide arguments favoring the existence of recurrent mumps attacks, the age, symptomatology, and humoral response of these patients (group 1) were compared to that of 82 randomly selected true primary infected patients (group 2), 10 parainfluenza virus-infected patients (group 3), and 20 noninfected mumps-immune subjects (group 4). Enzyme-linked immunosorbent assay (ELISA) procedures with different viral antigenic preparations were used for determination of specific IgM, IgA, IgG, IgG subclasses, and IgG avidity. The patients of group 1, older than those of group 2 (28 vs. 10 years, P < 0.0001), presented a significantly less severe and less typical symptomatology. Against the whole virus they exhibited IgG of higher avidity (P < 0.001), a lower prevalence and titer of IgA (10 vs. 68%, P < 0.0001 and 278 vs. 5,009, P < 0.001, respectively). Values obtained for IgG 1, 2, and 3 were significantly different between the two groups. Prevalence and absorbance of nucleocapsid-directed IgG 3 were significantly lower in group 1 (27 vs. 46%, P < 0.01 and 0.444 vs. 0.869, P < 0.01, respectively). A significant discrepancy also allowed patients from group 1 to be distinguished from those of groups 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption/desorption of human serum albumin on hydroxyapatite: a critical analysis of the Langmuir model

We studied the adsorption of human albumin onto synthetic hydroxyapatite, using a radiotracer technique and a special flow cell. Adsorption was studied under various conditions corresponding to different thermodynamic paths. It appears that (i) as is the usual case, the isotherms obtained within a short time range (a few hours) do not correspond to a true equilibrium situation; (ii) when the adsorption process is followed for longer times, which is necessary at low bulk concentrations, one always reaches the plateau surface adsorption; (iii) this plateau value is independent of the "history" of the adsorption process and corresponds well to the jamming limit predicted by the random sequential adsorption model; and (iv) surface denaturation, leading to enhanced surface binding and thus decreasing desorption constants, is the important phenomenon that can partly and qualitatively explain our observations. Its time dependence, however, remains to be clarified.

Desorption and exchange properties of adsorbed albumin on apatite. Influence of long-term interfacial residence times

A technique using 125I-labeled proteins was employed to study static adsorption properties and slow exchange and desorption processes of human albumin in contact with synthetic hydroxyapatite beads. With the aid of a thermostated "minicolumn," the adsorption isotherm was obtained during a so-called multiadsorption process, and could be described by a Langmuir adsorption model (K = 1.10 x 10(10) cm3.mol-1). All kinetic desorption and exchange experiments could be fitted by a simple exponential function of time. No influence of long-term interfacial residence times on characteristic relaxation times or percentage of desorbed or exchanged proteins could be detected in the present system. On the other hand, as compared to the low surface coverage domain, the small percentage of desorbable and high percentage of exchangeable molecules in the adsorption plateau domain was attributed to a bimolecular exchange process.

A modified Limulus amebocyte lysate test with increased sensitivity for detection of bacterial endotoxin

We have developed a simple modification of the chromogenic Limulus amebocyte lysate test that increases the sensitivity for the detection of bacterial endotoxins. In this assay, free paranitroaniline, cleaved from synthetic chromogenic substrates by proteases that were generated by Limulus lysate after incubation with endotoxin, was then derived. Derivation was with p-dimethylaminocinnamaldehyde in the presence of strong acid, forming a stable Schiff base end product with much greater molar absorbancy than the parent chromogen. Conditions (times and temperatures of incubations, concentrations of reagents) for the augmented chromogenic procedure were optimized. A ten-fold or greater increase in sensitivity for bacterial endotoxin was obtained with the modified assay as compared with the standard chromogenic Limulus test, with unequivocal detection of endotoxin concentrations of less than 100 pg/ml. The greater sensitivity of this modified Limulus test increases its usefulness for a wide range of research applications and clinical investigations.